1. Field of the Invention
The present invention relates to a high frequency coupler and a communication device for a communication machine that carries out bulk data transmission in a proximity distance by a weak UWB communication system using a wide bandwidth of a high frequency, and particularly to a high frequency coupler and a communication device having two or more communication spots at low cost and small space.
2. Description of the Related Art
Non-contact communication has been widely utilized as media for authentication information, electronic money, and other value information. Recently, as further applications of such non-contact communication, applications to bulk data transmission, such as downloading or streaming of video images, music, and the like, are examined.
Proximity wireless transfer techniques applicable to high speed communication may include “TransferJet®” using weak UWB (ultra wide band) signal (for example, refer to Japanese Unexamined Patent Application Publication No. 2008-99236 and www.transferjet.org/en/index.html (as of Jun. 23, 2009)). Such a proximity wireless transfer technique (TransferJet) is basically a system of signal transmission utilizing the coupling action of induction electric fields, and a communication device thereof is configured with a communication circuit unit processing a high frequency signal, a coupling electrode disposed separately at a certain height from a ground, and a resonator unit efficiently supplying the high frequency signal to the coupling electrode. A component including a coupling electrode or a coupling electrode and a resonator unit may also be called as a “high frequency coupler” herein.
Similar to NFC (near field communication) communications and the like from the past (NFC is standardized as ISO/IEC IS 18092), proximity wireless transfer systems can also be configured as a pair of a reader writer (initiator) sending a request command and a transponder (target) returning a response command.
Here, such a proximity wireless transfer system does not have to get a wireless station license by using weak wireless, and the communication distance is approximately 3 cm equivalent to a half wavelength of a used frequency band. Therefore, when carrying out proximity wireless transfer between two instruments respectively having a high frequency coupler mounted thereto, it is desirable to dispose coupling electrodes of each other coming close sufficiently.
One of typical utilization forms of proximity wireless transfer systems may include, as illustrated in FIG. 23, reading and writing information for a mobile instrument by placing a host instrument, such as a digital camera with a high frequency coupler built therein, on a reading surface of a reader writer, such as a personal computer or a cradle. However, since there is no industry standard on the shape of a housing and the installation site of a high frequency coupler in an instrument, an event is also considered that, depending on the combination of instruments, an installation method capable of proximity wireless transfer is not found in the utilization form of the illustration, that is, to become incapable of communication.
When there is only one communication spot in a high frequency coupler, it is prone to be in an event incapable of communication. For example, in order to facilitate acquisition of an optimal communication situation between the coupling electrodes of both, the configuration is proposed in which a plurality of high frequency couplers is disposed in an array (for example, refer to Japanese Unexamined Patent Application Publication No. 2008-131372). However, it is difficult to find a housing space for a plurality of high frequency couplers in an instrument in design, and the costs turns out to increase in accordance with the item number of high frequency couplers to be used.